Clutch assemblies with balance cavities formed by disc springs

ABSTRACT

Transmissions and clutch assemblies for transmissions are disclosed herein. A transmission includes an input shaft, an output shaft, and a clutch assembly. The input shaft is configured to receive rotational power. The output shaft is configured to transmit rotational power to a load. The clutch assembly is coupled between the input shaft and the output shaft to selectively transmit rotational power therebetween in use of the transmission. The clutch assembly includes a housing, a piston, and a disc spring. The piston is movable relative to the housing and cooperates with the housing to at least partially define a first cavity that is configured to receive hydraulic fluid such that a first centrifugal pressure force is created in use of the clutch assembly. The disc spring is movable relative to the housing.

RELATED APPLICATIONS

This application is a continuation of U.S. patent application Ser. No.16/405,525, filed May 7, 2019, the disclosure of which is herebyincorporated by reference in its entirety.

FIELD OF THE DISCLOSURE

The present disclosure relates, generally, to clutch assemblies, and,more specifically, to clutch assemblies incorporating disc springs.

BACKGROUND

In use of rotating clutches, supply of hydraulic fluid to a first cavityto cause movement of a piston or the like may be associated withgeneration of a first centrifugal pressure force. In some cases,centrifugal pressure forces may cause, or otherwise be associated with,undesirable movement of a piston or similar component. To resist suchmovement, hydraulic fluid may be supplied to a second cavity of arotating clutch to generate a second centrifugal pressure force thatcounteracts the first centrifugal pressure force. Devices and/or meansfor providing cavities that may be used to generate counteractingcentrifugal pressure forces remain an area of interest.

SUMMARY

The present disclosure may comprise one or more of the followingfeatures and combinations thereof.

According to one aspect of the present disclosure, a transmission mayinclude an input shaft, an output shaft, and a clutch assembly. Theinput shaft may be configured to receive rotational power. The outputshaft may be configured to transmit rotational power to a load. Theclutch assembly may be coupled between the input shaft and the outputshaft to selectively transmit rotational power therebetween in use ofthe transmission. The clutch assembly may have a housing, a piston, anda disc spring. The piston may be movable relative to the housing, andthe piston may cooperate with the housing to at least partially define afirst cavity that is configured to receive hydraulic fluid such that afirst centrifugal pressure force is created in use of the clutchassembly. The disc spring may be movable relative to the housing, andthe disc spring may cooperate with at least one of the housing and thepiston to at least partially define a second cavity that is configuredto receive hydraulic fluid such that a second centrifugal pressure forceis created that at least partially counteracts the first centrifugalpressure force in use of the clutch assembly.

In some embodiments, the clutch assembly may include a diaphragm incontact with the disc spring, and the diaphragm may be configured to atleast partially conform to the shape of the disc spring in response tomovement of the disc spring relative to the housing in use of the clutchassembly. A first side of the disc spring may contact the diaphragm anda second side of the disc spring arranged opposite the first side maycontact a retaining ring of the clutch assembly, and the retaining ringmay be constrained against movement relative to the housing in an axialdirection. The retaining ring may at least partially seal the secondcavity adjacent an inner diameter of the disc spring to resist leakageof hydraulic fluid from the second cavity in use of the clutch assembly.

In some embodiments, the first side of the disc spring may face thepiston. Additionally, in some embodiments, the diaphragm may cooperatewith the disc spring, the housing, and the piston to at least partiallydefine the second cavity. Further, in some embodiments still, the clutchassembly may include a sealing element that contacts the diaphragm andthe piston to at least partially seal the second cavity adjacent anouter diameter of the disc spring to resist leakage of hydraulic fluidfrom the second cavity in use of the clutch assembly.

In some embodiments, the clutch assembly may include a spring seatarranged in contact with the piston and the disc spring, and the springseat may cooperate with the disc spring and the piston to at leastpartially define the second cavity. The clutch assembly may include asealing element arranged in contact with the spring seat and the discspring to seal the second cavity adjacent an outer diameter of the discspring to resist leakage of hydraulic fluid from the second cavity inuse of the clutch assembly.

In some embodiments, the clutch assembly may include a spring seat incontact with the disc spring and a retaining ring that is affixed to thehousing such that the spring seat is constrained against axial movementrelative to the housing. The clutch assembly may include a sealingelement arranged in contact with the disc spring and the spring seat toat least partially seal the second cavity adjacent an inner diameter ofthe disc spring to resist leakage of hydraulic fluid from the secondcavity in use of the clutch assembly.

In some embodiments, the second cavity may at least be partially definedby only one piston included in the clutch assembly. Additionally, insome embodiments, the disc spring may be movable relative to the housingin response to movement of the piston relative to the housing in use ofthe clutch assembly.

According to another aspect of the present disclosure, a rotating clutchassembly for a transmission may include a housing, a piston, and a discspring. The piston may be movable relative to the housing, and thepiston may cooperate with the housing to at least partially define afirst cavity that is configured to receive hydraulic fluid such that afirst centrifugal pressure force is created in use of the clutchassembly. The disc spring may be movable relative to the housing, andthe disc spring may cooperate with at least one of the housing and thepiston to at least partially define a second cavity that is configuredto receive hydraulic fluid such that a second centrifugal pressure forceis created that at least partially counteracts the first centrifugalpressure force in use of the clutch assembly.

In some embodiments, the clutch assembly may include a diaphragm incontact with the disc spring that is configured to at least partiallyconform to the shape of the disc spring in response to movement of thedisc spring relative to the housing in use of the clutch assembly, andthe diaphragm may cooperate with the disc spring, the housing, and thepiston to at least partially define the second cavity.

In some embodiments, the clutch assembly may include a spring seatarranged in contact with the piston and the disc spring that cooperateswith the disc spring and the piston to at least partially define thesecond cavity, and the clutch assembly may include a sealing elementarranged in contact with the spring seat and the disc spring to seal thesecond cavity adjacent to an outer diameter of the disc spring to resistleakage of hydraulic fluid from the second cavity in use of the clutchassembly.

In some embodiments, the second cavity may at least be partially definedby only one piston included in the clutch assembly, and the disc springmay be movable relative to the housing in response to movement of thepiston relative to the housing in use of the clutch assembly.

According to yet another aspect of the present disclosure, a rotatingclutch assembly for a transmission may include a housing, a piston, adisc spring, and a diaphragm. The piston may be movable relative to thehousing, and the piston may cooperate with the housing to at leastpartially define a first cavity that is configured to receive hydraulicfluid such that a first centrifugal pressure force is created in use ofthe clutch assembly. The disc spring may be movable relative to thehousing. The diaphragm may be in contact with the disc spring. The discspring and the diaphragm may cooperate with at least one of the housingand the piston to at least partially define a second cavity that isconfigured to receive hydraulic fluid such that a second centrifugalpressure force is created that at least partially counteracts the firstcentrifugal pressure force in use of the clutch assembly.

In some embodiments, the diaphragm may be configured to at leastpartially conform to the shape of the disc spring in response tomovement of the disc spring relative to the housing in use of the clutchassembly. A first side of the disc spring may contact the diaphragm andface the piston and a second side of the disc spring arranged oppositethe first side may contact a retaining ring of the clutch assembly, andthe retaining ring may be constrained against movement relative to thehousing in an axial direction.

These and other features of the present disclosure will become moreapparent from the following description of the illustrative embodiments.

BRIEF DESCRIPTION OF THE DRAWINGS

The invention described herein is illustrated by way of example and notby way of limitation in the accompanying figures. For simplicity andclarity of illustration, elements illustrated in the figures are notnecessarily drawn to scale. For example, the dimensions of some elementsmay be exaggerated relative to other elements for clarity. Further,where considered appropriate, reference labels have been repeated amongthe figures to indicate corresponding or analogous elements.

FIG. 1 is a partially diagrammatic view of a transmission;

FIG. 2 is a sectional view taken about line 2-2 of a clutch assemblyadapted for use in the transmission of FIG. 1, with the clutch assemblyin a disengaged state;

FIG. 3 is a sectional view of the clutch assembly shown in FIG. 2, withthe clutch assembly in an engaged state;

FIG. 4 is a sectional view of another clutch assembly adapted for use ina transmission, with the clutch assembly in a disengaged state; and

FIG. 5 is a sectional view of the clutch assembly shown in FIG. 4, withthe clutch assembly in an engaged state.

DETAILED DESCRIPTION

While the concepts of the present disclosure are susceptible to variousmodifications and alternative forms, specific embodiments thereof havebeen shown by way of example in the drawings and will be describedherein in detail. It should be understood, however, that there is nointent to limit the concepts of the present disclosure to the particularforms disclosed, but on the contrary, the intention is to cover allmodifications, equivalents, and alternatives consistent with the presentdisclosure and the appended claims.

References in the specification to “one embodiment,” “an embodiment,”“an illustrative embodiment,” etc., indicate that the embodimentdescribed may include a particular feature, structure, orcharacteristic, but every embodiment may or may not necessarily includethat particular feature, structure, or characteristic. Moreover, suchphrases are not necessarily referring to the same embodiment. Further,when a particular feature, structure, or characteristic is described inconnection with an embodiment, it is submitted that it is within theknowledge of one skilled in the art to effect such feature, structure,or characteristic in connection with other embodiments whether or notexplicitly described. Additionally, it should be appreciated that itemsincluded in a list in the form of “at least one A, B, and C” can mean(A); (B); (C); (A and B); (A and C); (B and C); or (A, B, and C).Similarly, items listed in the form of “at least one of A, B, or C” canmean (A); (B); (C); (A and B); (A and C); (B and C); or (A, B, and C).

In the drawings, some structural or method features, such as thoserepresenting devices, modules, instructions blocks and data elements,may be shown in specific arrangements and/or orderings for ease ofdescription. However, it should be appreciated that such specificarrangements and/or orderings may not be required. Rather, in someembodiments, such features may be arranged in a different manner and/ororder than shown in the illustrative figures. Additionally, theinclusion of a structural or method feature in a particular figure isnot meant to imply that such feature is required in all embodiments and,in some embodiments, may not be included or may be combined with otherfeatures.

In some embodiments, schematic elements used to represent blocks of amethod may be manually performed by a user. In other embodiments,implementation of those schematic elements may be automated using anysuitable form of machine-readable instruction, such as software orfirmware applications, programs, functions, modules, routines,processes, procedures, plug-ins, applets, widgets, code fragments and/orothers, for example, and each such instruction may be implemented usingany suitable programming language, library, application programminginterface (API), and/or other software development tools. For instance,in some embodiments, the schematic elements may be implemented usingJava, C++, and/or other programming languages. Similarly, schematicelements used to represent data or information may be implemented usingany suitable electronic arrangement or structure, such as a register,data store, table, record, array, index, hash, map, tree, list, graph,file (of any file type), folder, directory, database, and/or others, forexample.

Further, in the drawings, where connecting elements, such as solid ordashed lines or arrows, are used to illustrate a connection,relationship, or association between or among two or more otherschematic elements, the absence of any such connection elements is notmeant to imply that no connection, relationship, or association canexist. In other words, some connections, relationships, or associationsbetween elements may not be shown in the drawings so as not to obscurethe disclosure. In addition, for ease of illustration, a singleconnecting element may be used to represent multiple connections,relationships, or associations between elements. For example, where aconnecting element represents a communication of signals, data orinstructions, it should be understood by those skilled in the art thatsuch element may represent one or multiple signal paths (e.g., a bus),as may be needed, to effect the communication.

Referring now to FIG. 1, an illustrative transmission 100 includes anumber of components that are depicted diagrammatically for the sake ofsimplicity and/or clarity. Those components include, but are not limitedto, an input shaft 102 and an output shaft 104. The input shaft 102 isconfigured to receive rotational power from a rotational power source(not shown) such as a motor or drive unit, for example. The output shaft104 is configured to transmit rotational power provided to the inputshaft 102 to a load (not shown) such as a differential and/or one ormore wheels, for example. In the illustrative embodiment, a clutchassembly 110 is coupled between the input shaft 102 and the output shaft104 to selectively transmit rotational power therebetween in use of thetransmission 100. The clutch assembly 110 is illustratively embodied as,or otherwise includes, a rotating clutch assembly 110.

It should be appreciated that the illustrative transmission 100, and theclutch assembly 110 thereof, are adapted for a variety of uses. Thetransmission 100 and the clutch assembly 110 may be adapted for use aspowertrain and/or drivetrain components of a vehicle usable in a varietyof applications. In one respect, the transmission 100 and the clutchassembly 110 may be adapted for use as components of an agriculturalharvesting vehicle, which may be used in in lawn and garden,construction, landscaping and ground care, golf and sports turf,forestry, engine and drivetrain, and government and militaryapplications, for example. In that respect, the transmission 100 and theclutch assembly 110 may be included in, or otherwise adapted for usewith, tractors, front end loaders, scraper systems, cutters andshredders, hay and forage equipment, planting equipment, seedingequipment, sprayers and applicators, tillage equipment, utilityvehicles, mowers, dump trucks, backhoes, track loaders, crawler loaders,dozers, excavators, motor graders, skid steers, tractor loaders, wheelloaders, rakes, aerators, skidders, bunchers, forwarders, harvesters,swing machines, knuckleboom loaders, diesel engines, axles, planetarygear drives, pump drives, generators, and marine engines, among othersuitable equipment.

Referring now to FIG. 2, the illustrative clutch assembly 110 includes ahousing 212, a piston 214, and a disc spring 216. The housing 212 may beformed separately from, or integrally with, a main housing (not shown)of the transmission 100 that houses the input shaft 102 and the outputshaft 104, among other things. The piston or apply piston 214 and thedisc spring 216 are each movable relative to the housing 212. The piston214 cooperates with the housing 212 to at least partially define acavity 220 that is configured to receive hydraulic fluid such that acentrifugal pressure force F1 is created in use of the clutch assembly110 (e.g., as a result of movement of hydraulic fluid in the cavity220). The disc spring 216 cooperates with at least one of the housing212 and the piston 214 to at least partially define a cavity 230 that isconfigured to receive hydraulic fluid such that a centrifugal pressureforce F2 is created (e.g., as a result of movement of hydraulic fluid inthe cavity 230) that at least partially counteracts the centrifugalpressure force F1 in use of the clutch assembly 110.

The illustrative clutch assembly 110 includes a diaphragm 222 arrangedin contact with the disc spring 216. The diaphragm 222 is configured toat least partially conform to the shape of the disc spring 216 inresponse to movement of the disc spring 216 relative to the housing 212in use of the clutch assembly 110. To facilitate such conformance, thediaphragm 222 may be formed from one or more materials capable ofresilient deflection and/or deformation, such as one or more polymericmaterials, for example. Of course, it should be appreciated that thediaphragm 222 may have another construction suitable for conformancewith the shape of the disc spring 216 in use of the clutch assembly 110.

In the illustrative embodiment, the diaphragm 222 cooperates with thedisc spring 216, the housing 212, and the piston 214 to at leastpartially define the cavity 230. Because the centrifugal pressure forceF2 at least partially counteracts the centrifugal pressure force F1 inuse of the clutch assembly 110, forces associated with the cavity 230may be said to balance forces associated with the cavity 220. In thatsense, the cavity 230 may be said to be a balance cavity. In any case,the cavity 230 is at least partially defined by only one piston (i.e.,the piston 214) included in the clutch assembly 110.

The illustrative clutch assembly 110 does not include a balance pistonor balance dam separate from the piston 214 which may be present inconventional configurations. Consequently, unlike other configurations,the balance cavity 230 is defined without provision of a balance pistonor a balance dam to do so. Provision of the disc spring 216 and thediaphragm 222 in the illustrative clutch assembly 110 obviates any needfor a separate balance piston or a balance dam.

In the illustrative embodiment, the disc spring 216 is formed to includefeatures 218 that might permit the flow of hydraulic fluid (e.g.,hydraulic fluid received in the cavity 230) through the disc spring 216if the diaphragm 222 was omitted from the clutch assembly 110. Thefeatures 218 may include, or otherwise be embodied as, fingers or slots,for example. Regardless, to resist leakage of hydraulic fluid from thecavity 230 through the disc spring 216 in use of the clutch assembly110, the diaphragm 222 is mated with the disc spring 216 to close offthe features 218.

An illustrative side 217 of the disc spring 216 contacts the diaphragm222 and faces the piston 214. The side 217 is arranged opposite a side219 of the disc spring 216 that contacts a retaining ring 224 of theillustrative clutch assembly 110. The retaining ring 224 seats in anotch 226 formed in the housing 212 such that the retaining ring 224 isconstrained against movement relative to the housing 212 in an axialdirection indicated by arrow A. As a result, the retaining ring 224constrains the disc spring 216 and the diaphragm 222 against movementrelative to the housing 212 in the axial direction A in use of theclutch assembly 110.

The illustrative cavity 230 is sealed by the retaining ring 224 and asealing element 228 arranged outward of the retaining ring 224 in aradial direction indicated by arrow R. The retaining ring 224 at leastpartially seals the cavity 230 adjacent an inner diameter ID of the discspring 216 to resist leakage of hydraulic fluid from the cavity 230 inuse of the clutch assembly 110. The sealing element 228 contacts thediaphragm 222 and the piston 214 to at least partially seal the cavity230 adjacent an outer diameter OD of the disc spring 216 to resistleakage of hydraulic fluid from the cavity 230 in use of the clutchassembly 110. The sealing element 228 may be embodied as, or otherwiseinclude, any one of a number of suitable sealing elements, such as arope seal, an O-ring, a labyrinth seal, a gasket, a diaphragm seal, aboss seal, a face seal, or the like, for example.

In the illustrative embodiment, the cavity 220 is sealed adjacent aradially-innermost portion P1 of the piston 214 and adjacent aradially-outermost portion P2 of the piston 214. More specifically, thecavity 220 is at least partially sealed adjacent the portion P1 by aretainer 232 and adjacent the portion P2 by a retainer 234. The retainer232 is received by a notch 236 formed in the housing 212 and theretainer 234 is received by a notch 238 formed in the piston 214. Theretainers 232, 234 may each be embodied as, or otherwise include, anyelement suitable to at least partially seal the cavity 220 to resistleakage of hydraulic fluid therefrom in use of the clutch assembly 110,and also suitable to accommodate movement of the piston 214 relative tothe housing 212 in the axial direction A in use of the clutch assembly110. For example, in some embodiments, the retainers 232, 234 may eachbe embodied as, or otherwise include, a rope seal, an O-ring, alabyrinth seal, a gasket, a diaphragm seal, a boss seal, a face seal, orthe like.

Feed ports 220P, 230P formed in the housing 212 are illustrativelyfluidly coupled to the respective cavities 220, 230 to supply hydraulicfluid thereto in use of the clutch assembly 110. It should beappreciated that hydraulic fluid may be conducted through the clutchassembly 110 (e.g., through a central shaft 210 thereof) so thathydraulic fluid may be provided to the ports 220P, 230P in use of theclutch assembly 110. Furthermore, it should be appreciated thathydraulic fluid supplied to the cavities 220, 230 by the respective feedports 220P, 230P may be exhausted, evacuated, or otherwise expelled fromthe cavities 220, 230 by discharge ports (not shown) in use of theclutch assembly 110.

The illustrative clutch assembly 110 includes a clutch pack 240configured for selective interaction with the piston 214 as described ingreater detail below. The clutch pack 240 is arranged between thehousing 212 and a clutch hub 250. In the illustrative embodiment, theclutch pack 240 includes friction plates 242 and reaction plates 244interposed between the friction plates 242. The friction plates 242 andthe reaction plates 244 are coupled to a backing plate 252. It should beappreciated that in some embodiments, the friction plates 242 may bebiased away from the reaction plates 244 by one or more biasing elements(not shown). In any case, the friction plates 242 may be configured forselective interaction with the reaction plates 244 to permit the clutchpack 240 to selectively transmit rotational power in use of the clutchassembly 110. More specifically, the friction plates 242 may beconfigured for selective interaction with the reaction plates 244 topermit the clutch pack 240 to selectively transmit rotation power froman input of the clutch assembly 110 (e.g., the clutch hub 250) to anoutput of the clutch assembly 110 (e.g., the backing plate 252) in usethereof. Therefore, in the illustrative embodiment, the clutch hub 250and the backing plate 252 provide an input and an output, respectively,of the clutch assembly 110.

In the illustrative embodiment, a radial space 254 is arranged betweenthe clutch hub 250 and the housing 212. In some embodiments, a system(not shown) separate from the arrangement incorporating the disc spring216 may be positioned in the radial space 254. In such embodiments, theseparate system may be positioned in the radial space 254 adjacent to,and/or in contact with, the retaining ring 224.

Operation of the illustrative clutch assembly 110 in a disengaged state260 will now be described with reference to FIG. 2. In the illustrativedisengaged state 260 of the clutch assembly 110, hydraulic fluid issupplied to the cavity 220 via the feed port 220P such that the piston214 is spaced from the clutch pack 240 (i.e., the friction plates 242 ofthe clutch pack 240) in the axial direction A. Consequently, norotational power is transmitted through the clutch pack 240 (e.g., fromthe clutch hub 250 to the backing plate 252) when the clutch assembly110 is in the disengaged state 260. To counteract the centrifugal forceF1 that may be associated with movement of hydraulic fluid provided tothe cavity 220 when the piston 214 is in the position shown in FIG. 2,hydraulic fluid may be supplied to the cavity 230 to create thecentrifugal force F2. It should be appreciated that the illustrativeclutch assembly 110 may include, or otherwise be adapted for use with,an electro-hydraulic control system (not shown) having a controllercommunicatively coupled to one or more valves (e.g., solenoid valves)such that control signals provided to the one or more valves by thecontroller may direct actuation of the one or more valves to supplyhydraulic fluid to, and exhaust hydraulic fluid from, the cavities 220,230 via the feed ports 220P, 230P.

Referring now to FIG. 3, operation of the illustrative clutch assembly110 in an engaged state 362 will now be described. In the illustrativeengaged state 362 of the clutch assembly 110, hydraulic fluid issupplied to the cavity 220 via the feed port 220P to advance the piston214 to the right in the axial direction A (i.e., relative to theposition of the piston 214 shown in FIG. 2) such that the piston 214 isin contact with the clutch pack 240 (i.e., one of the friction plates242 of the clutch pack 240). Due at least in part to axial forceprovided by the piston 214, rotational power may be transmitted throughthe clutch pack 240 (e.g., from the clutch hub 250 to the backing plate252) when the clutch assembly 110 is in the engaged state 362. Inresponse to movement of the piston 214 to the right in the axialdirection A relative to the housing 212, the diaphragm 222 and the discspring 216 move together relative to the housing 212. That is, thediaphragm 222 and the disc spring 216 rotate together about an axis 364Athat extends into the page such that the diaphragm 222 and the discspring 216 are substantially more upright when the clutch assembly 110is in the engaged state 362 than when the clutch assembly 110 is in thedisengaged state 260. To counteract the centrifugal force F1 that may beassociated with movement of hydraulic fluid provided to the cavity 220when the piston 214 is in the position shown in FIG. 3, hydraulic fluidmay be supplied to the cavity 230 to create the centrifugal force F2.

Referring now to FIG. 4, an illustrative clutch assembly 410 is adaptedfor use with, and may be included in, the transmission 100, at least insome embodiments. The illustrative clutch assembly 410 includes ahousing 412, a piston 414, and a disc spring 416. The housing 412 may beformed separately from, or integrally with, a main housing (not shown)of the transmission 100. The piston or apply piston 414 and the discspring 416 are each movable relative to the housing 412. The piston 414cooperates with the housing 412 to at least partially define a cavity420 that is configured to receive hydraulic fluid such that acentrifugal pressure force F4 is created in use of the clutch assembly410 (e.g., as a result of movement of hydraulic fluid in the cavity420). The disc spring 416 cooperates with at least one of the housing412 and the piston 414 to at least partially define a cavity 430 that isconfigured to receive hydraulic fluid such that a centrifugal pressureforce F5 is created (e.g., as a result of movement of hydraulic fluid inthe cavity 430) that at least partially counteracts the centrifugalpressure force F4 in use of the clutch assembly 410.

In the illustrative embodiment, the disc spring 416, the housing 412,and the piston 414 cooperate to at least partially define the cavity430. Because the centrifugal pressure force F5 at least partiallycounteracts the centrifugal pressure force F4 in use of the clutchassembly 410, forces associated with the cavity 430 may be said tobalance forces associated with the cavity 420. In that sense, the cavity430 may be said to be a balance cavity. In any case, the cavity 430 isat least partially defined by only one piston (i.e., the piston 414)included in the clutch assembly 410.

The illustrative clutch assembly 410 does not include a balance pistonor balance dam separate from the piston 414 which may be present inconventional configurations. Consequently, unlike other configurations,the balance cavity 430 is defined without provision of a balance pistonor a balance dam to do so. Provision of the disc spring 416 in theillustrative clutch assembly 410 obviates any need for a separatebalance piston or a balance dam.

In the illustrative embodiment, the disc spring 416 is formed withoutfeatures (such as features 218) that might permit the flow of hydraulicfluid (e.g., hydraulic fluid received in the cavity 430) through thedisc spring 216. Accordingly, the illustrative clutch assembly 410 omitsa diaphragm (e.g., such as the diaphragm 222).

The illustrative clutch assembly 410 includes a spring seat 418 thatcooperates with the disc spring 416, the housing 412, and the piston 414to at least partially define the cavity 430. The spring seat 418provides a connection interface between the disc spring 416 and thehousing 412 and is arranged adjacent an inner diameter ID′ of the discspring 416 in contact with the disc spring 416 and a retaining ring 420that is affixed to the housing 412. As a result, the spring seat 418 isconstrained against movement relative to the housing 412 in an axialdirection indicated by arrow A′. In some embodiments, the spring seat418 may provide one or more sealing features that facilitate sealing ofthe cavity 430. The retaining ring 420 seats in a notch 422 formed inthe housing 412. Consequently, the retaining ring 420 constrains thedisc spring 416 against movement relative to the housing 412 in theaxial direction A′ in use of the clutch assembly 410.

The illustrative clutch assembly 410 includes a sealing element 424arranged in contact with the disc spring 416 and the spring seat 418 toat least partially seal the cavity 430. That is, the sealing element 424is arranged in contact with the disc spring 416 and the spring seat 418to at least partially seal the cavity 430 adjacent the inner diameterID′ of the disc spring 416 to resist leakage of hydraulic fluid from thecavity 430 in use of the clutch assembly 410. The sealing element 424may be embodied as, or otherwise include, any one of a number ofsuitable sealing elements, such as a rope seal, an O-ring, a labyrinthseal, a gasket, a diaphragm seal, a boss seal, a face seal, or the like,for example.

The illustrative clutch assembly 410 includes a spring seat 432 thatcooperates with the spring seat 418, the disc spring 416, the housing412, and the piston 414 to at least partially define the cavity 430. Thespring seat 432 has a generally C-shaped cross-section and is arrangedin contact with the piston 414 and the disc spring 416. The spring seat432 provides a connection interface between the piston 414 and the discspring 416 and, in some embodiments, may provide one or more sealingfeatures that facilitate sealing of the cavity 430. A sealing element434 is arranged radially between the spring seat 432 and the piston 414.In addition, a sealing element 436 is arranged in contact with thespring seat 432 and the disc spring 416 to seal the cavity 430 adjacentan outer diameter OD′ of the disc spring 416 to resist leakage ofhydraulic fluid from the cavity 430 in use of the clutch assembly 410.Each of the sealing elements 434, 436 may be embodied as, or otherwiseinclude, any one of a number of suitable sealing elements, such as arope seal, an O-ring, a labyrinth seal, a gasket, a diaphragm seal, aboss seal, a face seal, or the like, for example.

Feed ports 420P, 430P formed in the housing 412 are illustrativelyfluidly coupled to the respective cavities 420, 430 to supply hydraulicfluid thereto in use of the clutch assembly 410. It should beappreciated that hydraulic fluid may be conducted through the clutchassembly 410 (e.g., through a central shaft 411 thereof) so thathydraulic fluid may be provided to the ports 420P, 430P in use of theclutch assembly 410. Furthermore, it should be appreciated thathydraulic fluid supplied to the cavities 420, 430 by the respective feedports 420P, 430P may be exhausted, evacuated, or otherwise expelled fromthe cavities 420, 430 by discharge ports (not shown) in use of theclutch assembly 410.

The illustrative clutch assembly 410 includes a clutch pack 440configured for selective interaction with the piston 414 as described ingreater detail below. The clutch pack 440 is arranged between thehousing 412 and a clutch hub 450. In the illustrative embodiment, theclutch pack 440 includes friction plates 442 and reaction plates 444interposed between the friction plates 442. The friction plates 442 andthe reaction plates 444 are coupled to a backing plate 452. It should beappreciated that in some embodiments, the friction plates 442 may bebiased away from the reaction plates 444 by one or more biasing elements(not shown). In any case, the friction plates 442 may be configured forselective interaction with the reaction plates 444 to permit the clutchpack 440 to selectively transmit rotational power (e.g., to the backingplate 452) in use of the clutch assembly 410. More specifically, thefriction plates 442 may be configured for selective interaction with thereaction plates 444 to permit the clutch pack 440 to selectivelytransmit rotation power from an input of the clutch assembly 410 (e.g.,the clutch hub 450) to an output of the clutch assembly 410 (e.g., thebacking plate 452) in use thereof. Therefore, in the illustrativeembodiment, the clutch hub 450 and the backing plate 452 provide aninput and an output, respectively, of the clutch assembly 410.

In the illustrative embodiment, a radial space 454 is arranged betweenthe clutch hub 450 and the housing 412. In some embodiments, a system(not shown) separate from the arrangement incorporating the disc spring416 may be positioned in the radial space 454. In such embodiments, theseparate system may be positioned in the radial space 454 adjacent to,and/or in contact with, the spring seat 418.

Operation of the illustrative clutch assembly 410 in a disengaged state460 will now be described with reference to FIG. 4. In the illustrativedisengaged state 460 of the clutch assembly 410, hydraulic fluid issupplied to the cavity 420 via the feed port 420P such that the piston414 is spaced from the clutch pack 440 (i.e., the friction plates 442 ofthe clutch pack 440) in the axial direction A′. Consequently, norotational power is transmitted through the clutch pack 440 (e.g., fromthe clutch hub 450 to the backing plate 452) when the clutch assembly410 is in the disengaged state 460. To counteract the centrifugal forceF4 that may be associated with movement of hydraulic fluid provided tothe cavity 420 when the piston 414 is in the position shown in FIG. 4,hydraulic fluid may be supplied to the cavity 430 to create thecentrifugal force F5. It should be appreciated that the illustrativeclutch assembly 410 may include, or otherwise be adapted for use with,an electro-hydraulic control system (not shown) having a controllercommunicatively coupled to one or more valves (e.g., solenoid valves)such that control signals provided to the one or more valves by thecontroller may direct actuation of the one or more valves to supplyhydraulic fluid to, and exhaust hydraulic fluid from, the cavities 420,430 via the feed ports 420P, 430P.

Referring now to FIG. 5, operation of the illustrative clutch assembly410 in an engaged state 562 will now be described. In the illustrativeengaged state 562 of the clutch assembly 410, hydraulic fluid issupplied to the cavity 420 via the feed port 420P to advance the piston414 to the right in the axial direction A′ (i.e., relative to theposition of the piston 414 shown in FIG. 4) such that the piston 414 isin contact with the clutch pack 440 (i.e., one of the friction plates442 of the clutch pack 440). Due at least in part to axial forceprovided by the piston 414, rotational power may be transmitted throughthe clutch pack 440 (e.g., from the clutch hub 450 to the backing plate452) when the clutch assembly 410 is in the engaged state 562. Inresponse to movement of the piston 414 to the right in the axialdirection A′ relative to the housing 412, the disc spring 416 movesrelative to the housing 412. That is, the disc spring 416 rotates aboutan axis 564A that extends into the page such that the disc spring 416 issubstantially more upright when the clutch assembly 410 is in theengaged state 562 than when the clutch assembly 410 is in the disengagedstate 460. To counteract the centrifugal force F4 that may be associatedwith movement of hydraulic fluid provided to the cavity 420 when thepiston 414 is in the position shown in FIG. 5, hydraulic fluid may besupplied to the cavity 430 to create the centrifugal force F5.

While the disclosure has been illustrated and described in detail in theforegoing drawings and description, the same is to be considered asexemplary and not restrictive in character, it being understood thatonly illustrative embodiments thereof have been shown and described andthat all changes and modifications that come within the spirit of thedisclosure are desired to be protected.

The invention claimed is:
 1. A transmission comprising: an input shaftconfigured to receive rotational power; an output shaft configured totransmit rotational power to a load; and a clutch assembly coupledbetween the input shaft and the output shaft to selectively transmitrotational power therebetween in use of the transmission, the clutchassembly including a housing, a piston movable relative to the housing,wherein the piston cooperates with the housing to at least partiallydefine a first cavity that is configured to receive hydraulic fluid suchthat a first centrifugal pressure force is created in use of the clutchassembly, a disc spring movable relative to the housing, wherein thedisc spring cooperates with at least one of the housing and the pistonto at least partially define a second cavity that is configured toreceive hydraulic fluid such that a second centrifugal pressure force iscreated that at least partially counteracts the first centrifugalpressure force in use of the clutch assembly; a first spring seatarranged in contact with the piston and the disc spring adjacent anouter diameter of the disc spring that cooperates with the disc springand the piston to at least partially define the second cavity; and asecond spring seat arranged in contact with the housing and the discspring adjacent an inner diameter of the disc spring that cooperateswith the disc spring, the piston, and the housing to at least partiallydefine the second cavity.
 2. The transmission of claim 1, furthercomprising a first sealing element arranged in contact with the firstspring seat and the disc spring to seal the second cavity adjacent theouter diameter of the disc spring to resist leakage of hydraulic fluidfrom the second cavity in use of the clutch assembly.
 3. Thetransmission of claim 2, further comprising a second sealing elementarranged in contact with the second spring seat and the disc spring toseal the second cavity adjacent the inner diameter of the disc spring toresist leakage of hydraulic fluid from the second cavity in use of theclutch assembly.
 4. The transmission of claim 3, further comprising athird sealing element arranged radially between the first spring seatand the housing.
 5. The transmission of claim 1, wherein the secondspring seat is constrained against movement relative to the housing inan axial direction.
 6. The transmission of claim 5, wherein the secondspring seat is constrained against movement relative to the housing inthe axial direction by a retaining ring seated in a notch formed in thehousing.
 7. The transmission of claim 1, wherein the first spring seathas a C-shaped cross section.
 8. The transmission of claim 1, whereinthe second cavity is at least partially defined by only one pistonincluded in the clutch assembly, and wherein the disc spring is movablerelative to the housing in response to movement of the piston relativeto the housing in use of the clutch assembly.
 9. The transmission ofclaim 1, wherein the clutch assembly includes a diaphragm in contactwith the disc spring that is configured to at least partially conform tothe shape of the disc spring in response to movement of the disc springrelative to the housing in use of the clutch assembly, and wherein thediaphragm cooperates with the disc spring, the housing, and the pistonto at least partially define the second cavity.
 10. A rotating clutchassembly for a transmission, the clutch assembly comprising: a housing,a piston movable relative to the housing, wherein the piston cooperateswith the housing to at least partially define a first cavity that isconfigured to receive hydraulic fluid such that a first centrifugalpressure force is created in use of the clutch assembly, a disc springmovable relative to the housing, wherein the disc spring cooperates withat least one of the housing and the piston to at least partially definea second cavity that is configured to receive hydraulic fluid such thata second centrifugal pressure force is created that at least partiallycounteracts the first centrifugal pressure force in use of the clutchassembly; a first spring seat arranged in contact with the piston andthe disc spring adjacent an outer diameter of the disc spring thatcooperates with the disc spring and the piston to at least partiallydefine the second cavity; and a second spring seat arranged in contactwith the housing and the disc spring adjacent an inner diameter of thedisc spring that cooperates with the disc spring, the piston, and thehousing to at least partially define the second cavity.
 11. The clutchassembly of claim 10, further comprising a sealing element arranged incontact with the first spring seat and the disc spring to seal thesecond cavity adjacent the outer diameter of the disc spring to resistleakage of hydraulic fluid from the second cavity in use of the clutchassembly.
 12. The clutch assembly of claim 10, further comprising asealing element arranged in contact with the second spring seat and thedisc spring to seal the second cavity adjacent the inner diameter of thedisc spring to resist leakage of hydraulic fluid from the second cavityin use of the clutch assembly.
 13. The clutch assembly of claim 10,further comprising a sealing element arranged radially between the firstspring seat and the housing.
 14. The clutch assembly of claim 10,wherein the second spring seat is constrained against movement relativeto the housing in an axial direction by a retaining ring seated in anotch formed in the housing.
 15. The clutch assembly of claim 10,wherein the second cavity is at least partially defined by only onepiston included in the clutch assembly, and wherein the disc spring ismovable relative to the housing in response to movement of the pistonrelative to the housing in use of the clutch assembly.
 16. The clutchassembly of claim 10, further comprising a diaphragm in contact with thedisc spring that is configured to at least partially conform to theshape of the disc spring in response to movement of the disc springrelative to the housing in use of the clutch assembly, and wherein thediaphragm cooperates with the disc spring, the housing, and the pistonto at least partially define the second cavity.
 17. The clutch assemblyof claim 10, wherein the disc spring is formed without features that maypermit flow of hydraulic fluid therethrough in use of the clutchassembly.
 18. The clutch assembly of claim 10, wherein the first springseat has a C-shaped cross section.